A patron of the Monastery of Guimarães,[1], he first appears in the curia regis of King Ferdinand I of León in 1059, and with the title of count for the first time in 1070 when he appears confirming a donation made by King Garcia II. He married Goncina[3] with whom he appears on 17 February 1071 making a donation to the Monastery of Santo Antonino de Barbudo of some properties in Luivão, not far from Cávado, confirming as Ego comes Nunus Menendiz et uxor mea comitissa domna Goncina ("I, count Nuno Menéndez and my wife countess dona Goncina").[4] He owned properties in Nogueira, Santa Tecla, Dadim, Cerqueda, Gualtar, and Barros, which were probably confiscated after his defeat and given later by King Alfonso VI of León to his son-in-law Sisnando.[3] Although the battle of Pedroso has been mistakenly dated in January of that year, as mentioned in the Chronica Gothorum, this donation proves that the battle took place in February rather than in January.[5]

With his wife Goncina, he had at least one daughter, Loba "Aurevelido" Nunes, who married Sisnando Davides, the parents of Elvira Sisnandes whose husband, Count Martim Moniz, son of Munio Fromarigues, succeeded Sisnando as the governor of the county.[6][7][3] He could also have been the father of Count Gómez Núñez and his brother Count Fernando.[8][a]

^According to Portuguese sources, Count Gómez was the son of Count Nuño Velázquez. Nevertheless, Nuño Velázquez appears in a charter dated 1070 at the Monastery of Sahagún with his wife Fronilde Sánchez and his children, Alfonso, Menendo, Sancho, and Elvira Núñez with no mention of a son named Gómez.[8] Fernando Núñez also appears with his wife Mayor Rodríguez in a charter dated 29 December 1127 making a donation to Ourense Cathedral of his part in the Monastery of Santa María de Porqueira which, as he states, he had inherited from his grandmother Goncina and from his father Nuño (Mídiz) Menéndez. Moreover, Gómez Núñez also appears in 1138 donating a property that he had inherited from Countess Goncina, "my father's mother" and a few years earlier, in 1126, he made another donation to the Cluny Abbey in which he mentions his brother Fernando Núñez.[9]